Which of the following is not classified as a disorder of the oil glands?

The correct answer is psoriasis, as it is primarily classified as a skin condition rather than a disorder specifically affecting the oil glands. Psoriasis is an autoimmune disease characterized by the rapid growth of skin cells that leads to scaling and inflammation, and it is associated with various factors including genetics and the immune system, rather than being linked to the function or dysfunction of oil glands.

In contrast, acne, seborrhea, and chloasma are all directly related to the function of oil glands. Acne results from the clogging of hair follicles with oil and dead skin cells, often exacerbated by the activities of oil glands. Seborrhea involves excessive oiliness and can lead to conditions such as seborrheic dermatitis, where overactive oil glands produce an abundance of sebum. Chloasma, while primarily related to pigmentation changes, is often influenced by hormonal factors that can also affect oil production and skin condition. Therefore, psoriasis stands apart as it does not primarily involve the oil glands, making it the correct choice for this question.